Ultrastructural classification of decidual stromal cells and their distribution during organ culture.

Decidua parietalis in the early stage of gestation were cultured for 96 hours using the organ culture method. The cultured explants were observed under electron microscopes and the prolactin concentrations of the mediums and of the tissues were measured by radioimmunoassay to study their endocrinological activity. The following five characteristic components of decidual cells were ultrastructurally selected to type the cells: 1) thickness of external lamina, 2) chromatin patterns of nuclei, 3) amounts of cytoplasmic organelles, 4) existence of dilatation of cisternae of rough endoplasmic reticulum and 5) existence of peduncular cytoplasmic processes and reflexive gap junctions. Using these five characteristics, the decidual stromal cells were classified into 3 types. After the organ culture had set for 96 hours, Type III cells increased and massive amounts of prolactin were detectable in the mediums.